The safest time of day to get heart surgery

Planning to have open heart surgery anytime soon? You might want to ask your cardiologist to book an afternoon slot in the OR.

New research shows that heart operations performed in the afternoon produced better outcomes than those done in the morning.

Because afternoon heart surgery syncs with the body’s circadian clock (the internal body clock that controls when people sleep, eat and wake up), it reduces the risk of heart damage, the French researchers said.

“Currently, there are few other surgical options to reduce the risk of post-surgery heart damage, meaning new techniques to protect patients are needed,” said study author Dr. David Montaigne, a professor at the University of Lille.

In one part of the study, his team tracked the medical records of nearly 600 people who had heart valve replacement surgery for 500 days, to identify any major cardiac events such as a heart attack, heart failure or death from heart disease. Half had surgery in the morning while the other half had it in the afternoon.

The risk of a major cardiac event was 50 percent lower among patients who had surgery in the afternoon than in those who had surgery in the morning. That would work out to one less major cardiac event per 11 patients who have afternoon surgery, the researchers said.

In another part of the study, the researchers monitored the health of 88 heart valve replacement surgery patients until they left the hospital. During the average follow-up of 12 days, patients who had afternoon surgery had less heart tissue damage than those who had morning surgery.

The researchers then tested 30 heart tissue samples from this group of patients and found that samples from afternoon surgery patients more quickly regained their ability to contract when put in conditions that replicated the heart refilling with blood.

Genetic analysis of the heart tissue samples also revealed that 287 genes linked to the circadian clock were more active in the samples from afternoon surgery patients than those from morning surgery patients.

“Our study found that post-surgery heart damage is more common among people who have heart surgery in the morning, compared to the afternoon,” Montaigne said in a journal news release.

“Our findings suggest this is because part of the biological mechanism behind the damage is affected by a person’s circadian clock, and the underlying genes that control it. As a result, moving heart surgery to the afternoon may help to reduce a person’s risk of heart damage after surgery,” he added.

Montaigne and his colleagues also said it may be possible to develop drugs that can influence circadian clock-related genes to protect the heart during surgery.